One type of web proxy product accelerates clients' access to web content via web caching. In general, these products cache web objects that were returned to clients, and use those cached objects for subsequent client requests, thereby saving the expense of making additional calls to the web server that provides the content.
However, web proxies act as a public cache, and are therefore not allowed to cache any private content that is targeted to a specific user, e.g., when authentication is required to obtain an authenticated objects. A well-known standard, RFC 2616, defines that if an authentication request (e.g., an HTTP “401 Unauthorized” status code) is returned as a response to an object request, an authenticated connection resulting from a completed authentication process is required to receive that content, and the web proxy cannot cache any additional content that is received using the authenticated connection. As a result, web proxies are not very successful in caching content from web sites that include authenticated content. Moreover, web proxies are also not very affective in caching content from web sites that have both authenticated and unauthenticated content, because unauthenticated content cannot be cached if an authenticated content was already provided on the same connection.